generally removing windscreen.
remove chrome trim and push it from the inside GENTLY, get someone on the outside so it does not fall onto the body. neeless to say push at the edges NOT in the centre.
the string trick is when fitting a long peice of string is wrapped round the rubber wich will by now be fitted to the new screen and while someone is holding it in place pull slowly on the string and this helps locate the rubber over the bodywork lip which holds the screen in place. the silver trim is replaced and all that is left to do is to wait for the next evil stone to b**ger up you hard work